# Gmx mmpbsa

**URL:** <https://gromacs.bioexcel.eu/t/gmx-mmpbsa/6765>\
**Category:** User discussions\
**Created:** [July 6, 2023, 2:31pm UTC](https://gromacs.bioexcel.eu/t/gmx-mmpbsa/6765 "2023-07-06T14:31:22Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![averdino](https://avatars.discourse-cdn.com/v4/letter/a/e5b9ba/32.png) [@averdino](https://gromacs.bioexcel.eu/u/averdino)\
**Post date:** [July 6, 2023, 2:31pm UTC](https://gromacs.bioexcel.eu/t/gmx-mmpbsa/6765/1 "2023-07-06T14:31:22Z")

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Problem with gmx\_MMPBSA----\> I gave the following command:  
gmx\_MMPBSA -O -i mmpbsa.in -cs full\_mdp.tpr -ci complex.ndx -cg 1 14 -ct trj.xtc -cp topol.top -o final.dat -do final2.dat\<\<\<\<\<\<\<\<\<\<\<\<\<\<\<\<\<\<\<\<\<\<\<\<\<\<\<\<\<\<\<\<\<\<\<\<\<\<\<\<\<\<\<\<\<\<\<\<\<\< but I obtained this error CalcError with REC.prmtop!What is this problem ? In addition  
I used charmm-gui and gromacs for simulations. Should I have converted the topology file or some other file? Or does the command do it automatically?